Import one dll to another dll

[starface245]

I created my own DLL which does exporting. Now I wanna do imports, I want to load the same function from another import function DLL (ex. user32.dll). I tried to do LoadLibrary, it does load the DLL but nothing is being imported in my DLL.

Basically I want to see my DLL IAT has user32.dll with all the functions in the IAT.

[Duthomhas]

I don't understand the question.

Are you trying to make your DLL export the same function as one in user32.dll?

[Computergeek01]

First, I am assuming that IAT stands for Import Address Table? If not then skip the rest of this post.

You're going about this wrong. What you would do in this case is write your executable to mediate communication between the two DLL's. You do this with Function Pointers and Call Backs, not by mergeing two tables and hoping for they work. Now, if what you're trying to do is make sure that a call to a function normally in user32.dll actually gets processed by your Lib, then that's a different story.

[starface245]

I'm trying to do this

User32.dll --> (import) --> My DLL

Where does windows xp keep their Lib for all their dll's?

[anonymous23323124]

I should imagine User32.lib comes with the Windows SDK. I certainly have a copy of it in there.

[Computergeek01]

User32.lib does indeed come with the Windows SDK, I'm looking at it right now in fact. But if you are using another compiler then you'll want to use the lib that came with that one instead. For example, I use MingW so I would use the file "libuser32.a" in order to access the functions in that DLL.

[anonymous23323124]

@Computergeek Where would one get libuser32.a? It doesn't come with MinGW, does it? And I can't imagine Microsoft providing one.

[Computergeek01]

It comes with MingW, under the lib folder. It's just an import library made for that dll made by MingW.

[anonymous23323124]

My bad - I didn't look hard enough for it in the MinGW directory. It was there though.

[starface245]

Anyone know where I can get Windows SDK offline?

EDIT: I found the offline version.

[Computergeek01]

I cannot tell you how happy I am that you edited this two minutes after you asked that question.

[starface245]

@computergeek01

If I look under PEview, it does not show any IAT(import address table) in my dll. How do I load my IAT into my dll from the functions of user32.dll? Without writing an exe, this has to be done in the dll.

I did go under properties -> linker->input->additional dependencies , add the user32.lib but I see nothing any IAT in my dll.

[Computergeek01]

Are you trying to statically link to this DLL? I only ask because that isn't what your first question sounded like.

Also, IDE are you using?

[starface245]

I just want my dll that has IAT with functions from user32.dll. That is my goal.
I'm using Visual Studio 2010.

[Computergeek01]

That's not how you're supposed to use DLL's though... I'm certain this is possible but because I've never wanted to do it I'll have to look it up.

[starface245]

No luck with this :(

#pragma comment(lib, "user32.lib")
#pragma comment(linker, "/include:AnyPopup") 

Basically, user32.dll has export function called AnyPopup which that function should be import into my IAT dll.

My IAT should show the function AnyPopup from user32.dll

[bartoli]

I don't understand the SOURCE of the problem.
When you will need to call AnyPopup from your Exe (the one that you want to call AnyPopup from your DLL right at the moment), you will need to declare it first right? For that, you will have to include the system header file in which it is declared, and then you will just need to link user32.lib in the Exe and that's it.
Are you for some reason forbidden to include user32.lib directly in the Exe, but in the need to use one of it's functions?
Also, when you include that header for the declaration of AnyPopup in your DLL, the symbol of AnyPopup is declared as imported in your DLL. FOr it to be visible in the export table of your DLL, it would have to be declared as exported.

[starface245]

@bartoli

Yes, I am forbidden to do anything in the exe. This all has to be done in my DLL. AnyPopup is just a short example, but I do have to use all the functions in user32.dll.

All the imports and exports has to be done in my DLL.

[modoran]

What are you really trying to do ? Sounds like hooking user32.dll, in which case look at Microsoft Detours library.

[starface245]

Yes, it hooking user32.dll(exports) to my DLL(imports), but I am not modifying any functions. I am just trying to get all the export functions in user32.dll into my import address table (IAT) in my DLL.